Fluid operated cylinder



Dec. 1, 1959 w. NEINER FLUID OPERATED CYLINDER Filed Sept. 30, 1957 D S F l n -N a ED INVENTOR. WARREN L. NEINER BY Wgll fllbhl/z/ .O m l mm mm vm mm mm ATTORNEYS United States Patent This invention relates to fluid operated cylinders and more specifically to a fluid cylinder in which a cushioning action is provided to dampen end limits of-rectilinear 1 travel of a piston and piston rod; t

in fluid cylinders generally, including air cylinders, it is desirable to prevent the piston from striking the ends of the housing at the end of a stroke. Various mechanisms have been proposed to cushionthe shock of the piston striking the ends of the housing. I

The major object of this invention is to provide a cushioned fluid cylinder to dampen the end of the stroke against an impact stop, and yet provide full piston exposure instantly upon application of reversal.

Another object of this invention is to provide a closed I circuit dashpotsystern for a power piston, wherein one fluid cushion'is at one limit of piston travel and another fluid cushion is at the other limit of piston travel, and the fluid cushions are interconnected by a restricted orifice having substantially no expansion reservoir.

0ne of the principal objects of the present invention is to provide a novel and improved dashpot type cushioning mechanism for absorbing and dampening the shock imparted by the piston at the end of its stroke.

'Anotherobject of the invention is to provide a'nove and improved dashpot mechanism for cushioning travel of the power piston, which'mechanism includes first and second dashpot pistons and a sealed fluid reservoir connecting the first and second dashpot pistons through a restricted fluid passage which inhibits movement of one of the dashpot cylinderswhen the one dashpot piston is contacted by the power cylinder.

Another and related object of the invention is to provide a novel and improved dashpot mechanism as outlined in connection with the foregoing objects wherein dampening movement of the one dashpot piston; when it is contacted by the power piston, will cause theother dashpot piston to shift into position to dampen the power piston movement when the power piston contacts said other piston.

Still another object of the inventionis to provide a novel I and improved fluid cylinder dashpot type cushioning de vice in which the dashpot has a sealed quantity of dampening fluid, a restricted passage for metering the flow of such fluid, and a needle valve to adjust the degree of restricseen from a plane indicated by the line 22 of Figure l.

Referring to the drawings, a housing is shown generally at iii. The housing has a central sleeve 11. The sleeve is closed by first and second end caps 12, 13. The end caps are held in close abutment with the center sleeve 11 by strainrods 14 and nuts '15.

The housing sleeve 11 has a bore 17 defining a power piston chamber 18. The power piston 19 is carried in the chamber for reciprocation. The power piston 19 is shiftable in fluid tight sliding engagement with the bore 17. A piston rod 20 is connected to the power piston 19. A connection is formed by a nut 21 threaded onto the end of the piston rod 20.

The first end closure 12, which is the left hand end closure in Figure 1, provides a rod bearing bore 26 and a packing gland 25 to guide rod 20, and seal against fluid oss.

A fluid passage 27 is provided at the first end of the housing 10 and in the disclosed embodiment the passage 27 is formed in the end closure cap 12. A second fluid passage 28 is provided at the second end of the housing 10 and preferably formed in the second end closure cap 13. The fluid passages 27, 28 are for the selective conduction of fluid under pressure to the power piston chamber 18. The'fluid passages 27, 28 are alternately intake and exhaust passages to permit the fluid under pressure to be introduced and exhausted from the chamber 18.

The previously described structure is well known in the art; It will be apparent that the subsequent description of a preferred form of the invention is susceptible to various alterations and modifications but it is hereinafter more fully described in connection with use in a fluid cylinder, preferably of the air actuated type.

The housing end closures 12, 13 have inwardly extending projections 29, 30 respectively. The projections 29, 30 have smooth cylindrically contoured outer surfaces 31, 32 respectively. The outer surfaces 31, 32 are of a substantially reduced diameter with respect to the surface 17.

The surface 31 and the surface 17 together define the radial extremities of an annular dashpot piston chamber 34. -The surfaces 17, 32 together define the radial extremities of a second annular piston dashpot chamber 35. 1 First and second dashpot pistons 36, 37 are carried in the first and second dashpot chambers 34, 35 respectively. The dashpot pistons 36, 37 have cylindrically contoured outer surfaces 39, 40 respectively. The dashpot piston outer surfaces 39, 40 are in a close sliding fluid tight fit with the surface 17. Each of the dashpot pistons 36, 37 have end closure projection contacting cylindrically contoured surfaces 41, 42 respectively. The projection contacting surfaces 41, 42 are in the sliding fluid tight fit with the projection outer surfaces 31, 32 respectively.

Suitable'packings designated by the letter P are carried by the dashpot pistons 36, 37. The packings P may take the form of O-rings. They-are interposed between the inner and outer surfaces of the dashpot pistons 36, 37 and the surfaces with which the dashpot piston surfaces coact.

The inward axial limits of the projection contacting surfaces 41, 42 are defined by shoulders 45, 46 respectively. The shoulders 45, 46 extend radially outwardly from the surfaces 41, 42. Snap rings 47, 48 coact with the shoulders 45, 46 respectively to limit the outward travel of the dashpot pistons 36, 37. v

A metering fluid passage 59, including a tube 62 connects the dashpot fluid chambers 34, 35. The dashpot chambers 34, 35 and the metering passage 50 together define a dashpot fluid reservoir of varying contour as will be subsequently described in more detail. The restriction of the metering passage 50 is adjusted by a needle valve shown generally at 51; The dashpot fluid reservoir, defined by the chambers 34, 35 and the passage 50, contains a sealed quantity of fluid. A fitting 60 communicates with the fluid passage 50 through a passage extension 61. The quantity of fluid contained in the dashpot reservoir is introduced through the fitting 60. The fluid can, from time to time, be replenished by introduction of additional fluid through thefitting 60. This may be required as replacement for fluid which leaks past any of the various packings.

In operation, fluid under pressure is first introduced through one of the fluid passages 27, 28. Referring to Figure I, it has been introduced through the passage 27 to drive the power piston 19 to the right. The power piston 19 has struck the dashpot piston 37 and caused the dashpot piston 37 to move to the right. This dashpot piston movement has forced the sealed dashpot fluid to pass through the metering passage 50 past the needle valve 51 and thence into the dashpot reservoir 34. Because of the restricted nature of the passage 50 this fluid flow is relatively slow and the motion of the power piston 19 was cushioned after contacting the piston 37. As the dash pot fluid entered the chamber 34 it forced the first or left hand dashpot piston 36 outwardly or to the right with respect to Figure 1. At the conclusion of a stroke to the right, which is the position of Figure 1, it will be seen that the dashpot piston 37 is in a fully retracted position and that the dashpot piston 36 is out against the snap ring 47 and ready to perform a dampening action.

Fluid under pressure is next introduced through the passage 28 which causes the power piston 19 to shift to the left with respect to Figure 1. There is no delay in applying full pressure to the entire piston face. Fluid is driven from the left hand portion of the power piston chamber 18 out through the passage 27. As the power piston 19 strikes the first dashpot piston 36 a dampening action: commences. Fluid is forced through the metering passage 56) from the dashpot chamber 34 into the dashpot chamber 35. Entrance of fluid into the dashpot-chamber 35 drives the dashpot piston 37 to the left with respect to Figure l and out against the snap ring 48.

It will thus be seen that a dashpot action is provided by a novel and improved dashpot mechanism which requires no external source of pressure or fluid. Further, the dashpot mechanism is self adjusting to meet whatever force is exerted by the power piston 19. While the dashpot mechanism has been described in great detail, in more concise terms it comprises essentially first and second dashpot pistons carried in first and second dashpot chambers, a metering fluid passage connecting the dashpot chambers, and a sealed quantity of fluid in the chambers and the metering passage. Thus a controllable dampening system is provided, without connection to outside fluid and with no interference with application of full power at the beginning of the power stroke.

Although the invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing fromthe spirit and the scope of the invention as hereinafter claimed. 4

I claim:

I. A fluid operated cylinder comprising, a housing having inner. walls defining an elongated through power piston chamber, a power piston reciprocal along a path of travel in the passage and having an outer surface in sliding fluid tight contact with the housing inner surface, said power piston chamber having first and second ends, said housing including a first fluid passage communicating with the power piston chamber first end and a second fluid passage communicating with the power piston chamber second end, said fluid passages being for the selective introduction of. fluid on either side of the power piston to cause the power piston to reciprocate in the power piston chamber, and a dashpot assembly, said dashpot assembly comprising, first and second dashpot pistons and metering fluid passage communicating with the dashpot pistons, the housing having first and second dashpot chambers communicating with the power piston chamber, said first dashpot piston being carried in the housing first dashpot chamber, said second dashpot piston being carried in the second dashpot chamber, said dashpot pistons being reciprocable along paths essentially parallel to said power piston path of travel, said dashpot pistons having first and second ends, the first dashpot piston first end being contacted by the power piston as the power piston concludes movement from the second to the first end of the power piston chamber, the second dashpot piston first end being in contact with said power piston as the power piston concludes movement from the first to the second end of the power piston chamber, said dashpot piston second ends being in communication with said metering fluid passage, the metering fluid passages and dashpot piston chambers together defining a closed fully hydraulic dashpot fluid reservoir of varying contour, the movement of one dashpot piston on contact by the power piston causing the movement of the other dashpot piston through confined flow of hydraulic fluid in the dashpot reservoir, and a packing means carried by said dashpot pistons in slidable fluid sealing contact with the walls of said dashpot chambers, whereby to provide a device in which a dashpot cushions the travel of the power pistons when the piston contacts one of the dashpot pistons which latter pistons will force fluid through a metering passage to move the other dash pot piston.

2. A fluid operated cylinder comprising, a housing having inner walls defining an elongated through power piston chamber, a power piston reciprocal along a path of travel in the passage and having an outer surface in sliding fluid tight contact with the housing inner surface, said power piston chamber having first and second ends, said housing including a first fluidpassage communicating with the power piston chamber first end and a second fluid passage communicating with the power piston chamber second end, said fluid passages being for the selective introduction' of fluid on either side of the power piston to cause the power piston to reciprocate in the power piston chamher, and a dashpot assembly, said dashpot assembly comprising, fist and second dashpot pistons and metering fluid passage communicating with the dashpot pistons, the housing having first and second dashpot chambers comrnunicating with the power piston chamber, said first dashpot piston being carried in the housing first dashpot chamber, said second dashpot piston being carried in the second dashpot chamber, said dashpot pistons being reciprocable along paths essentially parallel to said power piston path of travel, said dashpot pistons having first and second ends, the first dashpot piston first end being contacted by the power piston as the power piston concludes movement from the second to the first end of the power piston chamber, the second dashpot piston first end being in contact with said power piston as the power piston concludes movement from the first to the second end of the power piston chamber, said dashpot piston second ends being in communication with said metering fluid passage, the metering fluid passages and dashpot piston chambers together defining a closed fully hydraulic dashpot fluid reservoir of varying contour, the movement of; one dashpot piston on contact by the power piston causing the movement of the other dashpot piston through confined flow of hydraulic fluid in the dashpot reservoir, a packing means carried by said dashpot pistons in slidable fluid sealing contact with the walls of said dashpot chambers, and a needle valve in said metering fluid passages for adjusting the flow of fluid through said metering passages, whereby to provide a device in which a dashpot cushions the travel of the power pistons when the piston contacts one of the dashpot pistons which latter pistons will force fluid through a metering passage to move the other dashpot piston.

3. A fluid operated cylinder comprising, a housing having inner walls defining an elongated through power piston chamber, a power piston reciprocal along a path of travel in the passage and having an outer surface in sliding fluid tight contact with the housing inner surface, said power piston chamber having first and second ends, said housing including a first fluid passage communicating with the power piston chamber first end and a second fluid passage communicating with the power piston chamber second end, said fluid passages being for the-selective introduction of fluid on either side of the power piston to cause the power piston to reciprocate in the power piston chamber, and a dashpot assembly, said dashpot assembly comprising, first and second dashpot pistons and metering fluid passage communicating with the dashpot pistons, the housing having first and second dashpot chambers communicating with the power piston chamber, said first dashpot piston being carried in the housing first dashpot chamber, said second dashpot piston being carried in the second dashpot chamber, said dashpot pistons being reciprocable along paths essentially parallel to said power piston path of travel, said dashpot pistons having first and second ends, the first dashpot piston first end being contacted by the power piston as the power piston concludes movement from the second to the first end of the power piston chamber, the second dashpot piston first end being in contact with said power piston as the power piston concludes movement from the first to the second end of the power piston chamber, said dashpot piston second ends being in communication with said metering fluid passage, the metering fluid passages and dashpot piston chambers together defining a closed fully hydraulic dashpot fluid reservoir of varying contour, the movement ofone dashpot piston on contact by the power piston causing the movement of the other dashpot piston through confined flow of hydraulic fluid in the dashpot reservoir, pack.ng means carried by said dashpot pistons in slidable fluid sealing contact with the walls of said dashpot chambers,

and a quantity of fluid closed in the dashpot reservoir for metered transmission of force from one dashpot piston to the other, whereby to provide a device in which a dash pot cushions the travel of the power pistons when the piston contacts one of the dashpot pistons which latter pistons will force fluid through a metering passage to move the other dashpot piston.

4. A fluid cylinder mechanism comprising, a housing having a central sleeve and first and second end caps, the sleeve having first and second ends closed by the end caps, the sleeve having an inner surface defining a power piston chamber, a power piston carried in the power piston chamber for reciprocal movement, a piston rod connected to the power piston and projecting through one of the end caps, the end caps each having an inwardly extending dashpot projection, each of the projections having a smooth outer surface, the first dashpot projection and the sleeve inner surface together defining radial extremities of a first dashpot chamber, the second dashpot projection outer surface and the sleeve inner surface together defining radial extremities of a second dashpot chamber, first and second dashpot pistons carried in the first and second dashpot chambers respectively, the dashpot pistons each having a smooth outer surface in sliding contact with the sleeve inner surface, the first dashpot piston having a smooth inner surface in sliding contact with the first dashpot projection outer surface, the second dashpot piston having a smooth inner surface in sliding contact with the second dashpot projection outer surface, packings carried by the dashpot pistons to maintain fluid tight engagement between the dashpot piston surfaces and the associated surfaces, said dashpot pistons being reciprocal in said dashpot chambers, first and second stop means carried by the first and second dashpot projections respectively, the first stop means being to limit the travel of the first dashpot outward from the first dashpot chamber, the second stop means being to limit the travel of the second dashpot piston outward from the second dashpot chamber, a longitudinally extending conduit carried by said end caps, and said mechanism defining a closed fully hydraulic dashpot fluid metering passage connecting said first and said second dashpot chambers, said caps each having passages forming a portion of said metering passage and said longitudinally extending conduit defining the remainder of said metering passage and connecting said passage portions in said end caps.

5. In the environment of a fluid power piston and cylinder, the provision of an improved dashpot stroke dampening structure for said piston, comprising, a first auxiliary piston and cylinder at a first end of said cylinder, said first auxiliary piston extending into said power cylinder in a position to be contacted by said power piston near the end of a power piston stroke and to resist said power piston with a dashpot action, a second auxiliary piston and cylinder at the second end of said power cylinder of like construction and operation, and a closed fully hydraulic fluid system interconnecting said cylinders of the first and second auxiliary piston and cylinder respectively, said closed systems being the fluid reservoir for the system and hence operation of one cylinder requires like operation of the other, said closed system including a metering orifice means to regulate the rate of transfer of fluid therethrough.

References Cited in the file of this patent UNITED STATES PATENTS 899,795 Osmer Sept. 29, 1908 2,664,860 Levetus Jan. 5, 1954 2,783,743 'Pappas Mar. 5, 1957 

